Sprague Atom series electrolytic capacitors are legendary for their widespread use in amplifiers for over 50 years. They are great for tube amplifiers, power supplies, and industrial applications where they will be subjected to high heat, vibration and extreme operating conditions. They are an ideal, vintage-correct replacement for amplifiers using original Sprague or Mallory capacitors. Smaller sizes are black with green lettering and larger sizes are blue with black lettering. Made in the USA.